Fluorescent oligo(N‐phenylmaleimide)s via aerobic radical telomerization initiated by benzylic hydrocarbons: Catalytic effect of CoII/N‐hydroxyphthalimide pair

Radical oligomerization of N‐phenylmaleimide (NPMI) was performed in benzylic hydrocarbons as the solvent. The thermally induced oligomerization occurred only above 130 °C, with the initiation attributed to autoxidation of benzylic hydrocarbons as well as formation and dissociation of charge‐transfer complexes between benzylic hydrocarbons and maleimides. The end‐group analysis on oligo(N‐ethylmaleimide) prepared under similar conditions confirmed that the chain transfer to benzylic hydrocarbons was the primary fashion in forming oligomeric chains, and radical telomerization underlaid the oligomerization with benzylic hydrocarbons as both the solvent, the initiator and the telogen. Co^II/N‐hydroxyphthalimide (NHPI) pairs could catalyze the telomerization at 110 °C. In such a catalytic process, Co^II‐based oxidative complexes oxidized benzylic hydrocarbons and NHPI into benzylic radicals and phthalimide N‐oxyl (PINO), and benzylic hydrocarbons underwent hydrogen atom transfer (HAT) to PINO. Oligo(NPMI)s were formed via HAT with benzylic hydrocarbons and NHPI. These oligo(NPMI)s exhibited fluorescent properties with excitation at 270–350 nm and 400–550 nm and emission at 530–750 nm. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 3846–3857